1. 18
Air Pollution

2. Core Case Study: South Asia’s Massive Brown Clouds
The South Asian Brown Clouds
Stretch across much of India, Bangladesh, China, and the western Pacific Ocean
Air pollution connects the world
Pollutants can circle the globe in about two weeks
Stricter air pollution standards and continued shifts towards cleaner fuels are needed

3. The South Asia's Brown Clouds (cont'd.)
Figure 18.1: The South Asian Brown Clouds are gigantic clouds of dust, smoke, soot, and other pollutants that stretch over much of South Asia. One is visible here over eastern China.
Fig. 18-1a, p. 474

4. 18-1: What is the Nature of the Atmosphere?
The two innermost layers of the atmosphere
Troposphere – supports life
Stratosphere – contains the protective ozone layer

5. The Atmosphere Consists of Several Layers
Atmosphere – thin blanket of gases surrounding the Earth
Density – number of gas molecules per unit of air volume
Density decreases as you move higher in the atmosphere

6. Atmospheric pressure (millibars)
Temperature
Thermosphere
Mesosphere
Altitude (kilometers)
Altitude (miles)
Stratosphere
Figure 18.2: Natural capital.
The earth’s atmosphere is a dynamic system that includes four layers. The average temperature of the atmosphere varies with altitude (red line) and with differences in the absorption of incoming solar energy. Question: Why do you think most of the planet’s air is in the troposphere?
Ozone layer
Troposphere
Pressure
(Sea level)
Pressure = 1,000 millibars
at ground level
Temperature (˚C)
Fig. 18-2, p. 475

7. Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate
75–80% of Earth’s air mass
Closest to Earth's surface
Composition of gases
78% nitrogen; 21% oxygen
Rising and falling air currents and greenhouse gases play a major role in weather and climate

8. The Stratosphere Is Our Global Sunscreen
Similar composition to the troposphere except that it contains:
Much less water
Ozone layer (O3)
Filters 95% of harmful UV radiation
Allows life to exist on land

9. 18-2: What Are the Major Outdoor Pollution Problems?
Pollutants mix in the air to form industrial smog
Primarily as a result of burning coal and photochemical smog
Caused by emissions from motor vehicles, industrial facilities, and power plants

10. Air Pollution Comes from Natural and Human Sources
Air pollution – presence of chemicals in the atmosphere
Concentrations high enough to harm organisms, ecosystems, human-made materials, and to alter climate
Natural sources
Dust blown by wind
Pollutants from wildfires and volcanoes
Volatile organics released by plants

11. Air Pollution Comes from Natural and Human Sources (cont’d.)
Mostly in industrialized and/or urban areas
Stationary sources – power plants and industrial facilities
Mobile sources – motor vehicles

12. Some Pollutants in the Atmosphere Combine to Form Other Pollutants
Primary pollutants
Emitted directly into the air
Secondary pollutants
From reactions of primary pollutants

13. Sources and Types of Air Pollutants
Primary Pollutants CO
CO2
Secondary Pollutants
N2O
SO2 NO
NO2
CH4 and most
other hydrocarbons
SO3
HNO3
H2SO4
Most suspended particles
H2O2 O3
PANs
Most NO3– and SO42– salts
Natural Source
Stationary
Human Source
Figure 18.3: Human inputs of air pollutants come from mobile sources (such as cars) and stationary sources (such as industrial, power, and cement plants). Some primary air pollutants react with one another and with other chemicals in the air to form secondary air pollutants.
Human Source
Mobile
Fig. 18-3, p. 477

14. What Are the Major Outdoor Air Pollutants?
Carbon oxides
Carbon monoxide (CO); carbon dioxide (CO2)
Nitrogen oxides (NO) and nitric acid (HNO3)
Acid deposition; photochemical smog
Does the benefit of the lessened atmospheric warming due to the South Asian Brown Clouds outweigh their harmful effects?
Critical Thinking Question: Science Focus 18.1

15. What Are the Major Outdoor Air Pollutants? (cont’d.)
Sulfur dioxide (SO2) and sulfuric acid (H2SO4)
Particulates
Suspended particulate matter
Ozone
Volatile organic compounds (VOCs)
Methane

16. Chemical Reactions That Form Major Outdoor Air Pollutants
Table 18-1: Chemical Reaction That Form Major Outdoor Air Pollutants
Table 18-1, p. 480

17. Acid Deposition
Figure 18.4: Acid deposition and other forms of air pollution have damaged this statue in Rome, Italy. The nose and part of the forehead have been restored.
Fig. 18-4, p. 478

18. Case Study: Lead Is a Highly Toxic Pollutant
In air, water, soil, plants, and animals
Does not break down in the environment
Impacts human health and environment
Children are most vulnerable
Can cause death, brain damage, and paralysis
How can we reduce lead in the environment?

19. Burning Coal Produces Industrial Smog
Chemical composition of industrial smog
Sulfur dioxide, sulfuric acid, and suspended solid particles
Formed from the burning of fossil fuels
Carbon monoxide, carbon dioxide, and soot result
How are pollutants formed from burning coal and oil?

20. Carbon monoxide (CO) and
Ammonium sulfate [(NH4)2SO4]
Ammonia (NH3)
Sulfuric acid (H2SO4)
Water vapor (H2O)
Sulfur trioxide (SO 3 )
Oxygen (O2)
Sulfur dioxide (SO2)
Sulfur (S) in coal and oil
Carbon monoxide (CO) and
carbon dioxide (CO2)
Carbon (C) in coal and oil
Burning coal and oil
Oxygen (O2)
Note: This is a carry-over animation from 17e. No modifications have been made to the animation itself; we have simply updating the figure number and page number in the lower-right corner.
Figure 18.8: This is a greatly simplified model of how pollutants are formed when coal and oil are burned. The result is industrial smog.
Stepped Art
Fig. 18-8, p. 481

21. Sunlight Plus Cars Equals Photochemical Smog
VOCs + NOx + Heat + Sunlight yields:
Ground level O3 and other photochemical oxidants
Aldehydes
Other secondary pollutants

22. PANS and other pollutants Nitrogen (N) in fossil fuel
Photochemical Smog
PANS and other pollutants
Volatile organic compounds (VOCs)
Ozone (O3)
Oxygen (O2)
Nitric oxide (NO) + Oxygen atom (O)
Water vapor (H2O)
UV radiation
Hydrocarbons
Peroxyacyl nitrates (PANs)
Nitrogen dioxide (NO2)
Oxygen (O2)
Nitric oxide (NO)
Oxygen (O2)
Burning fossil fuels
Figure 18.9: A greatly simplified model of how the pollutants that make up photochemical smog are formed.
Nitrogen (N) in fossil fuel
Fig. 18-9, p. 483

23. Several Factors Can Decrease or Increase Outdoor Air Pollution
Outdoor air pollution may be decreased by:
Settling of particles due to gravity
Rain and snow
Salty sea spray from the ocean
Winds
Chemical reactions

24. Several Factors Can Decrease or Increase Outdoor Air Pollution (cont’d
Outdoor air pollution may be increased by:
Urban buildings
Hills and mountains
High temperatures
Emissions of VOCs from certain trees and plants
The grasshopper effect
Temperature inversions
Warm air above cool air prevents mixing

25. A Temperature Inversion
Warmer air
Descending warm air mass
Inversion layer
Inversion layer
Sea breeze
Increasing altitude
Figure 18.11: A temperature inversion, in which a warm air layer sits atop a cooler air layer, can take place in either of the two sets of topography and weather conditions shown here. Normally, the air temperature decreases steadily with increasing altitude within the troposphere, but during an inversion, there is a layer of air that is warmer than the cooler air above and below (see graph).
Decreasing temperature
Fig , p. 484

26. 18-3: What Is Acid Deposition and Why Is It a Problem?
Caused mainly by coal-burning power plants and motor vehicle emissions
Threatens human health, aquatic life and ecosystems, forests, and human-built structures in some regions

27. Acid Disposition Is a Serious Regional Air Pollution Problem
Acid deposition
Sulfuric acid and nitric acid compounds
Wet deposition – rain, snow, fog, cloud vapor
Dry deposition – particles
Substances remain in the atmosphere days
What are some ways in which your daily activities contribute to acid deposition?

28. Natural Capital Degradation: Acid Deposition
Wind
Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3)
Windborne ammonia gas
and some soil particles partially neutralize acids and form dry sulfate and nitrate salts
Wet acid deposition (droplets of H2SO4 and HNO3 dissolved
in rain and snow)
Nitric oxide (NO)
Sulfur dioxide (SO2) and NO
Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts)
Acid fog
Figure 18.12: Natural capital degradation.
Acid deposition, which consists of rain, snow, dust, or gas with a pH lower than 5.6, is commonly called acid rain. Soils and lakes vary in their ability to neutralize excess acidity.
Lakes in shallow
soil low in limestone become acidic
Lakes in deep soil high in limestone are buffered
Fig , p. 485

29. Current and Possible Future Acid Rain Problem Areas
Figure 18.13: This map shows regions where acid deposition is now a problem and regions with the potential to develop this problem. Such regions have large inputs of air pollution (mostly from power plants, industrial facilities, and ore smelters) or are sensitive areas with naturally acidic soils and bedrock that cannot neutralize (buffer) additional inputs of acidic compounds. Question: Do you live in or near an area that is affected by acid deposition or an area that is likely to be affected by acid deposition in the future? (Data from World Resources Institute and U.S. Environmental Protection Agency)
Fig , p. 486

30. Acid Deposition Has a Number of Harmful Effects
Human health
Respiratory disorders; toxins from fish
Release of toxic metals
Aquatic ecosystems
Lowers pH and kills organisms
Leaching of soil nutrients
Forest damage
Damage to buildings, etc.

31. Solutions Acid Deposition Prevention Cleanup
Reduce coal use and burn only low-sulfur coal
Add lime to neutralize acidified lakes
Use natural gas and renewable energy resources in place of coal
Add phosphate fertilizer to neutralize acidified lakes
Remove SO2 and NOx from smokestack gases and remove NOx from motor vehicular exhaust
Figure 18-15: There are several ways to reduce acid deposition and the damage. Questions: Which two of these solutions are the best ones? Why?
Add lime to neutralize acidified soils
Tax SO2 emissions
Fig , p. 488

32. 18-4: What Are the Major Indoor Air Pollution Problems?
The most threatening indoor air pollutants:
Smoke and soot from the burning of wood and coal in cooking fires (mostly in less- developed countries)
Cigarette smoke
Chemicals used in building materials and cleaning products

33. Indoor Air Pollution Is a Serious Problem
In developing countries
Indoor burning of wood, charcoal, dung, crop residues, coal
Greatest risk to low-income populations
In developed countries
Indoor air pollution is greater than outdoor air pollution
Chemicals used in building materials

34. Chloroform Source: Chlorine-treated water in hot showers
Possible threat: Cancer
Para-dichlorobenzene Source: Air fresheners, mothball crystals
Threat: Cancer
Tetrachloroethylene Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer
Formaldehyde
Source: Furniture stuffing, paneling, particleboard, foam insulation
Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness
1,1,1-Trichloroethane Source: Aerosol sprays Threat: Dizziness, irregular breathing
Styrene
Source: Carpets, plastic products
Threat: Kidney and liver damage
Nitrogen oxides Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches
Benzo-α-pyrene Source: Tobacco smoke, woodstoves Threat: Lung cancer
Particulates
Source: Pollen, pet dander, dust mites, cooking smoke particles
Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease
Figure Numerous indoor air pollutants are found in most modern homes. Question: To which of these pollutants are you exposed?
Radon-222
Source: Radioactive soil and rock surrounding foundation, water supply
Threat: Lung cancer
Tobacco smoke
Source: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease
Asbestos
Source: Pipe insulation, vinyl ceiling and floor tiles
Threat: Lung disease, lung cancer
Carbon monoxide
Source: Faulty furnaces, unvented gas stoves and kerosene heaters, woodstoves Threat: Headaches, drowsiness, irregular heartbeat, death
Methylene chloride Source: Paint strippers and thinners
Threat: Nerve disorders, diabetes
Fig , p. 489

35. Indoor Air Pollution Is a Serious Problem (cont’d.)
Indoor air pollution risk
Children under five and the elderly
Sick
Pregnant women
People with respiratory disorders or heart problems
Smokers
Factory workers

36. Indoor Air Pollution Is a Serious Problem (cont’d.)
Four most dangerous indoor air pollutants in more-developed countries
Tobacco smoke
Formaldehyde
Radioactive radon-222 gas
Very small (ultrafine) particles
Other indoor pollutants
Pesticide residues, lead particles, air-borne spores (mold, mildew)

37. Case Study: Radioactive Radon Gas
Sources
Underground deposits of certain minerals
Human health risks
Decays into Polonium-210
Can expose the lungs to high amounts of radiation
How can you test for and correct a radon problem?

38. Case Study: Radioactive Radon Gas (cont’d.)
Outlet vents for furnace, dryer, and woodstove
Open window
Cracks in wall
Openings around pipes
Slab joints
Wood stove
Cracks in floor
Sump pump
Clothes dryer
Furnace
Radon-222 gas
Slab
Figure 18.19: There are a number of ways that radon-222 gas can enter homes and other buildings. Question: Have you tested the indoor air where you live for radon-222?
Uranium-238
Soil
Fig , p. 491

39. 18-5: What Are the Health Effects of Air Pollution?
Air pollution can contribute to:
Asthma
Chronic bronchitis
Emphysema
Lung cancer
Heart attack
Stroke

40. Your Body’s Natural Defenses Against Air Pollution Can Be Overwhelmed
The respiratory system protects from air pollutants through:
Hair
Cilia
Mucus
Effects of smoking and prolonged air pollution exposure
Chronic bronchitis
Emphysema

41. Major Components of the Human Respiratory System
Epithelial cell
Cilia
Nasal cavity
Oral cavity
Goblet cell (secreting mucus)
Pharynx (throat)
Trachea (windpipe)
Mucus
Bronchus
Bronchioles
Alveolar duct
Right lung
Figure 18.21: Major components of the human respiratory system can help to protect you from air pollution, but these defenses can be overwhelmed or breached.
Bronchioles
Alveolar sac (sectioned)
Alveoli
Fig , p. 492

42. Air Pollution Is a Big Killer
3.2 million deaths per year worldwide
Mostly in Asia; 1.2 million in China
150,000 to 350,000 in the United States
EPA proposed stricter emission standards for diesel-powered vehicles
125,000 die in U.S. each year from diesel fumes
Emissions from one truck = 150 cars

43. Premature Deaths from Air Pollution in the U.S.
Figure 18.22: Distribution of premature deaths from air pollution in the United States, mostly from very small, fine, and ultra-fine particles added to the atmosphere by coal-burning power plants. Questions: Why do the highest death rates occur in the eastern half of the United States? If you live in the United States, what is the risk at your home or where you go to school?
Fig , p. 493

44. 18-6: How Should We Deal with Air Pollution?
Legal, economic, and technological tools can help us to clean up air pollution
However, the best solution is to prevent it

45. Laws and Regulations Can Reduce Outdoor Air Pollution
United States
Clean Air Acts: 1970, 1977, and 1990 created regulations enforced by states and cities
EPA
National ambient air quality standards for six outdoor pollutants
Carbon monoxide, nitrogen dioxide, sulfur dioxide, suspended particulate matter, ozone, and lead

46. Laws and Regulations Can Reduce Outdoor Air Pollution (cont’d.)
EPA’s national emission standards for 188 hazardous air pollutants (HAPs)
Toxic Release Inventory (TRI)
Some successes in the United States
Decrease in emissions
Use of low-sulfur diesel fuel
Less-developed countries
Have more challenges with reducing air pollution

47. We Can Use the Marketplace to Reduce Outdoor Air Pollution
Emission trading or cap-and-trade program
Success depends on:
How low initial cap is set
How often it is lowered

48. There Are Many Ways to Reduce Outdoor Air Pollution
Stationary source air pollution
Motor vehicle air pollution
Less-developed countries are far behind developed countries in implementing solutions
Non-existent and/or weak laws

49. Solutions Stationary Source Air Pollution Prevention
Reduction or Disposal
Burn low-sulfur coal or remove sulfur from coal
Disperse emissions (which can increase downwind pollution) with tall smokestacks
Convert coal to a liquid or gaseous fuel
Remove pollutants from smokestack gases
Figure There are several ways to prevent, reduce, or disperse emissions of sulfur oxides, nitrogen oxides, and particulate matter from stationary sources such as coal-burning power plants and industrial facilities (Concept 18-6). Questions: Which two of these solutions do you think are the most important? Why?
Switch from coal to natural gas and renewables
Tax each unit of pollution produced
Fig , p. 495

50. Motor Vehicle Air Pollution
Solutions
Motor Vehicle Air Pollution
Prevention
Cleanup
Walk bike or use mass transit
Require emission control devices
Inspect car exhaust systems twice a year
Improve fuel efficiency
Figure 18.26: There are a number of ways to prevent and reduce emissions from motor vehicles (Concept 18-6). To find out what and how much your car emits, go to Questions: Which two of these solutions do you think are the most important? Why?
Get older, polluting cars off the road
Set strict emission standards
Fig , p. 496

51. Reducing Indoor Air Pollution Should Be a Priority
Greater threat to human health than outdoor pollution
What can be done?
Prevention
Cleanup

52. Solutions Indoor Air Pollution Prevention Reduction and Dilution
Ban indoor smoking
Use adjustable fresh air vents
for work spaces
Set stricter formaldehyde emissions standards for carpet, furniture, and building materials
Circulate air more frequently
Circulate a building’s air through rooftop greenhouses
Figure 18.27: There are several ways to prevent or reduce indoor air pollution. Questions: Which two of these solutions do you think are the best ones? Why?
Prevent radon infiltration
Use less polluting cleaning agents, paints, and other products
Use efficient venting systems for wood-burning stoves
Fig , p. 496

53. We Can Emphasize Pollution Prevention
How can we avoid producing these pollutants in the first place?
Place political and economic pressure on government officials and companies

54. 18-17: How Have We Depleted Ozone in the Stratosphere & What Can We Do?
Widespread use of certain chemicals has:
Reduced ozone levels in the stratosphere
Allowed more harmful ultraviolet radiation to reach the earth’s surface
To reverse ozone depletion:
Stop producing ozone-depleting chemicals
Adhere to the international treaties that ban such chemicals

55. Our Use of Certain Chemicals Threatens the Ozone Layer
Ozone is thinning over Antarctica and the Arctic
Chlorofluorocarbons (CFCs)
Persistent chemicals that attack ozone in the stratosphere

56. Ozone Degradation
Figure 18-30: Natural Capital Degradation: These colorized satellite images show ozone thinning over Antarctica during September of 1980 (left), 2000 (center), and 2011 (right). Ozone depletion of 50% or more occurred in the dark blue and purple areas.
Fig , p. 498

57. Why Should We Worry About Ozone Depletion?
Ozone protects the earth’s surface from damaging UV radiation
Human health concerns
UV radiation affects plankton

58. We Can Reverse Stratospheric Ozone Depletion
Stop producing ozone-depleting chemicals immediately
Agreements with a prevention approach:
Montreal Protocol
Cut emissions of CFCs
Copenhagen Amendment
Accelerated phase-out

59. Big Ideas
Outdoor air pollution, in the forms of industrial smog, photochemical smog, and acid deposition, and indoor air pollution are serious global problems
Each year, at least 2.4 million people die prematurely from the effects of air pollution; indoor air pollution, primarily in less-developed countries, causes about two-thirds of those deaths

60. Big Ideas (cont’d.)
We need to give top priority status to the prevention of outdoor and indoor air pollution throughout the world and the reduction of stratospheric ozone depletion

61. Tying it All Together Three principles of sustainability
Rely more on direct and indirect forms of solar energy than on fossils fuels
Recycle and reuse much more of what we use
Use a diverse set of nonpolluting or low- polluting renewable energy resources